package com.rui.rw;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class ReadWriteLockDemo {
    public static void main(String[] args) {
        MyCacheLock myCacheLock = new MyCacheLock();

        //写
        for (int i = 0; i < 5; i++) {
            final int temp = i;
            new Thread(() -> {
                myCacheLock.put(String.valueOf(temp),temp);
            },String.valueOf(i)).start();
        }

        //读
        for (int i = 0; i < 5; i++) {
            final int temp = i;
            new Thread(() -> {
                myCacheLock.get(String.valueOf(temp));
            },String.valueOf(i)).start();
        }
    }
}

/**
 * 自定义缓存
 */

class MyCache {

    private volatile Map<String, Object> map = new HashMap<>();

    //写
    public void put(String key , Object value) {
        System.out.println(Thread.currentThread().getName() + "写入" + key);
        map.put(key, value);
        System.out.println(Thread.currentThread().getName() + "写入OK");
    }

    //读
    public void get(String key) {
        System.out.println(Thread.currentThread().getName() + "读取" + key);
        Object o = map.get(key);
        System.out.println(Thread.currentThread().getName() + "读取OK");
    }
}

class MyCacheLock {

    private volatile Map<String, Object> map = new HashMap<>();

    //读写锁，更加细粒度的控制
    private ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

    //写
    public void put(String key, Object value) {
        readWriteLock.writeLock().lock();
        try {
            System.out.println(Thread.currentThread().getName() + "写入" + key);
            map.put(key, value);
            System.out.println(Thread.currentThread().getName() + "写入OK");
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            readWriteLock.writeLock().unlock();
        }
    }

    //读
    public void get(String key) {
        readWriteLock.readLock().lock();
        try {
            System.out.println(Thread.currentThread().getName() + "读取" + key);
            Object o = map.get(key);
            System.out.println(Thread.currentThread().getName() + "读取OK");
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            readWriteLock.readLock().unlock();
        }
    }
}